Nail the cable to the rafters with clamps, insulate, clad, pull through the drywall at the appropriate place. You don't need foil. There is one under the roof tiles, that underlayment. It is supposed to be just a storage room. I wouldn't insulate it at all. Karsten
It's a matter of opinion. If it turns into a hobby room or something like that, insulate. If only Christmas stuff, suitcases, junk are stored there, a dry cold floor is sufficient. Also for drying laundry. But then open the Velux!
Because you need/want a nice dry storage place that is not so dependent on temperature?
I think that with proper construction, every attic should be dry... and despite insulation, it will get "very hot" up there in summer and always cool in winter... since it is unheated... of course not quite as much as if you completely forego it..
And to me, it sounds like the typical Christmas boxes + boxes with sorted-out stuff, etc.... an uninsulated attic would be enough for that too.